Sandbox 40



LYSOZYME
Lysozyme is an enzyme found in the secretions and tissues of most animals. It destroys bacterial cell walls by hydrolyzing the glycosidic linkages in cell wall peptidoglycans.

Structure
Lysozyme is made up of eight α-helices and three β- sheets and is 129 residues long. The enzyme's tertiary structure is maintained in part by disulfide bonds. The following view displays the enzyme from residue number 60 to 102. It shows two disulfide bonds stabilizing two alpha helices and the loop connecting them. Disulfide Bonds

This scene shows the same group of residues with the four cysteines responsible for the the disulfide bonds highlighted with yellow halos. Cysteines

As it is in all proteins, the hydrophobic effect is the strongest force that holds lysozyme's three-dimensional structure in place. In the following view, the hydrophilic residues are shown in purple and the hydrophobic residues are shown in gray. Hydrophobic View

This view focuses on the hydrophobic interactions of one helix of the enzyme. The helix is highlighted in yellow halos and its residues are shown in a space-filling model. The water molecules that are hydrogen-bonded to the helix are displayed as small purple spheres. The side chains of other hydrophobic residues that interact with the hydrophobic residues of the helix are shown as gray ball-and-stick structures. Helical Interactions

Active Site
In Lysozyme's active site, several residues form hydrogen bonds with the NAG and NAM rings of peptidoglycan. The following view shows these residues highlighted and shown in space-filling form. The substrate (peptidoglycan) is shown in green and the Hydrogen bonds formed between the residues and the substrate are represented by small green spheres. Active Site Hydrogen-Bonding

This next view shows the two Catalytic residues of Lysozyme, Glu 35 and Asp 52. These residues hydrogen-bind to the rings of peptidoglycan before hydrolyzing the bond between NAG and NAM. The two catalytic enzymes are blown up in a space-filling format and substrate is green. the hydrogen bond between the substrate and Asp52 is represented by a small green sphere (there is only one Hydrogen bond because the hydrolysis reaction has already taken place in this scene). Catalytic Residues